Engineering Commons^™

Effect Of Surface Fluid Entrapment In A Laminar Flat Plate Boundary Layer, Abigail Hays

Mechanical Engineering Research Theses and Dissertations

For streamlined objects in laminar flow, the drag is dominated by friction drag. To counteract this, the boundary condition of the object can be changed to introduce an apparent slip on the surface. A number of approaches have been proposed for introducing surface slip to reduce drag and viscous resistance in fluid flows. This work investigates a novel approach to providing slip via fluid entrapment in a perforated domain embedded in the surface. The fluid entrapment system uses a cavity underneath the domain to allow entrapment of fluid of the same type, or supply air to the surface perforations in …

Microparticle Propulsion For In Vivo Navigation, Louis Rogowski

Mechanical Engineering Research Theses and Dissertations

Microscale propulsion impacts a diverse array of fields, with simplistic microrobots allowing for novel innovations in microscale surgery and drug delivery. Propulsion at the microscale is constrained by physics, with time-reversal and geometric symmetries limiting available propulsion mechanisms. However, certain fluid environments and surface coatings allow for the propulsion of microparticles through externally applied magnetic fields. Presented here is a detailed analysis of microparticles propelling using spontaneous symmetry breaking, flagella surface coatings, and multi-modal actuation mechanisms. Spontaneous symmetry breaking in nonlinearly viscoelastic fluids is presented for the first time in literature, with two equal and opposite propulsion states existing along …

Homogenization Of Composite And Cellular Materials Incorporating Microstructure And Surface Energy Effects, Ahmad Gad

Mechanical Engineering Research Theses and Dissertations

In the last few decades, the popularity of composite and cellular materials has rapidly increased through their widespread applications in multiple engineering fields including aerospace, automotive, civil and biomedical. However, to a large extent, the success of their practical applications depends on our ability to predict their mechanical behavior by using high-fidelity mechanics models.

Micromechanical modeling of composite and cellular materials is a challenging task due to the heterogeneous nature of such materials and the interactions among various constituent phases at the microscopic level, which result in non-homogeneous deformation, strain and stress fields. Therefore, it is necessary to develop simple …

Critical Point Identification In 3d Velocity Fields, Mohammadreza Zharfa

Mechanical Engineering Research Theses and Dissertations

Classification of flow fields involving strong vortices such as those from bluff body wakes and animal locomotion can provide important insight to their hydrodynamic behavior. Previous work has successfully classified 2D flow fields based on critical points of the velocity field and the structure of an associated weighted graph using the critical points as vertices. The present work focuses on extension of this approach to 3D flows. To this end, we have used the Gauss-Bonnet theorem to find critical points and their indices in the 3D velocity vector field, which functions similarly to the Poincare-Bendixon theorem in 2D flow fields. …

Graphene-Based Water Desalination Using Atomistic Simulations, Thanh Chinh Nguyen

Mechanical Engineering Research Theses and Dissertations

My research focused on investigating saltwater transport through nanoporous graphene membranes using molecular dynamics (MD) simulations. Particularly, in this dissertation, we focused on pressure-driven flows of salt water through uncharged and charged nanoporous graphene membranes for water desalination applications. In the first study, desalination performance of uncharged single-layer nanoporous graphene membranes was observed based on volumetric flow rate, required pressure drop, and salt rejection efficiency. A functional relationship between the volumetric flow rate, pressure drop, pore diameter, and the dynamic viscosity of saltwater was also examined. In further studies, transport of salt ions through positively and negatively charged single-layer nanoporous …

Molecular Dynamics Studies On Nanoscale Confined Liquids, Alper Celebi

Mechanical Engineering Research Theses and Dissertations

Liquid transport in nanochannels have been attracting great interests, especially for last two decades, owing to its potential applicability in various fields including biochemistry, medical science and engineering. For exploring and generating new ideas in the field of nanofluidics, molecular simulation techniques have become an ideal way due to the experimental challenges impeding the field of nanofluidics in fabrication and measurements.

In this dissertation, we perform molecular dynamics simulations to investigate liquid transport behavior in nanoscale channels. The expanse of this dissertation concerns several fundamental topics in nanoscale liquid transport phenomena such as liquid properties in nanoscale confinements, interfacial flows …

Sandia Senior Design Collaboration: Vacuum Sensor Design, James L. Valerio, Eric J. Black, Joseph P. Bednarz, David R. Warther

Williams Honors College, Honors Research Projects

Sandia National Laboratories has requested a fully mechanical device to close a circuit after launch has occurred and the device enters a vacuum. Intended for applications in rockets and missiles, the device must fit in a 36 degree wedge with a 6.8 inch radius that is 6 inches in height and be ready to bolt onto a rocket. The pressure switch must be prevented from actuating until a launch acceleration ranging from 20 to 27g is detected. The pressure switch must close the circuit after a pressure of 10^-1 Torr is reached and before a pressure of 10^{-6 …}

Workspace Analysis Of A Linear Delta Robot: Calculating The Inscribed Radius, Michael Louis Pauly

Graduate Theses - Mechanical Engineering

One of the most important traits of a robotic manipulator is its work envelope, the space in which the robot can position its end effector. Parallel manipulators, while generally faster, are restricted by smaller work envelopes [1]. As such, understanding the parameters defining a physical robot’s work envelope is essential to the optimal design, selection, and use of robotic parallel manipulators. A Linear Delta Robot (LDR) is a type of parallel manipulator in which three prismatic joints move separate arms which connect to a single triangular end plate [2]. In this study, general inverse kinematics were derived for a linear …

Lightweight Uav Launcher, Ben Miller, Christian Valoria, Corinne Warnock, Jake Coutlee

Mechanical Engineering

This report discusses the design, construction, and testing of a lightweight, portable UAV launcher. There is a current need for a small team of soldiers to launch a US Marine Tier II UAV in a remote location without transport. Research was conducted into existing UAV launcher designs and the pros and cons of each were recorded. This research served as a basis for concept generation during the initial design development stage. It was required that the design weigh less than 110 lbs, occupy a smaller volume than 48" x 24" 18" in its collapsed state, be portable by a single …

The Collapsible Trailer: Design And Manufacture, Robert Hobson

Biomedical Engineering

No abstract provided.